60+ Xebia Interview Questions and Answers

Classes needed to create a GET REST API

• Controller class to handle the request

• Service class to perform business logic

• Repository class to interact with database

• Model class to define data structure

• RequestMapping annotation to map the URL

Types define the structure of data while interfaces define the behavior of classes. Types can be used for defining variables and parameters, while interfaces can be used for defining contracts for classes.

• Types define the structure of data, such as primitive types (int, string) or custom types (class, struct)

• Interfaces define the behavior that a class must implement, without specifying how it should be implemented

• Types are used for defining variables, parameters, return types...read more

Java 8 introduced several new features including lambda expressions, functional interfaces, streams, and default methods.

• Lambda expressions: Enable functional programming in Java by expressing instances of single-method interfaces (functional interfaces) concisely.

• Functional interfaces: Interfaces with a single abstract method, such as java.util.function.Function or java.util.function.Predicate.

• Streams: Allow for processing sequences of elements in a functional style, support...read more

Yes, I have worked on Kafka. My code had 10 partitions.

• Yes, I have experience working with Kafka and have implemented code with multiple partitions.

• In one of my projects, I used Kafka with 10 partitions to distribute the workload efficiently.

• Having multiple partitions in Kafka helped in achieving high throughput and scalability for real-time data processing.

Spring Boot is a framework built on top of Spring, providing additional features and simplifying configuration.

• Spring Boot provides auto-configuration, reducing the need for manual configuration

• Spring Boot includes an embedded server, making it easy to deploy applications

• Spring Boot provides a simpler project structure and reduces boilerplate code

• Spring Boot includes Actuator, which provides production-ready features like health checks and metrics

• Spring Boot is opinionated, p...read more

I would improve Google Maps by enhancing its real-time traffic updates and integrating more public transportation options.

• Improve real-time traffic updates to provide more accurate and timely information to users

• Integrate more public transportation options to provide users with more choices for getting around

• Enhance the user interface to make it more intuitive and user-friendly

• Add more detailed information about points of interest, such as reviews and ratings

• Improve the accur...read more

I can generate 100 qualified B2B leads with a minimum budget of $10,000.

• Utilize targeted email campaigns to reach potential B2B leads

• Leverage social media advertising to attract qualified leads

• Collaborate with industry influencers to generate leads through partnerships

An interface is a blueprint of a class. Default method is a method in an interface with a default implementation.

• An interface defines a set of methods that a class must implement

• Default method provides a default implementation for a method in an interface

• Default methods were introduced in Java 8

• Default methods can be overridden by implementing classes

HashMap is a data structure that stores key-value pairs. List is a collection of ordered elements.

• HashMap allows fast retrieval of values based on keys.

• List maintains the order of elements and allows duplicates.

• HashMap uses hashing to store and retrieve elements.

• List uses indexing to access elements.

• HashMap is not thread-safe while List is thread-safe.

• Example: HashMap map = new HashMap<>(); map.put("apple", 1);

• Example: List list = new ArrayList<>(); list.add("apple"); list.ad...read more

I will conduct a thorough audit of the website and collaterals to identify areas for improvement and implement necessary changes.

• Conduct a comprehensive audit of the website and collaterals to identify issues

• Ensure branding consistency across all platforms

• Optimize website for SEO and user experience

• Update content to be more engaging and relevant to target audience

• Implement A/B testing to optimize conversion rates

The class used to connect with the Database depends on the programming language and framework being used.

• In Java, the class used is usually DriverManager or DataSource.

• In Python, the class used is usually psycopg2 or mysql-connector.

• In PHP, the class used is usually PDO or mysqli.

• The specific class used may also depend on the type of database being used, such as MySQL, PostgreSQL, or MongoDB.

Eviction policy in cache determines which items should be removed when the cache reaches its maximum capacity.

• Eviction policy helps in managing the cache size and ensuring that the most relevant data is retained.

• Common eviction policies include LRU (Least Recently Used), LFU (Least Frequently Used), and FIFO (First In, First Out).

• For example, in LRU policy, the least recently accessed items are removed from the cache when it reaches its limit.

I have used Redis and Memcached. Cache is needed to improve performance by storing frequently accessed data in memory.

• Used Redis for key-value storage and Memcached for object caching

• Cache is needed to reduce database load and improve response time

• Helps in storing frequently accessed data in memory for quick retrieval

Angular is a framework for building client-side web applications.

• Angular is a front-end framework developed by Google.

• It allows developers to build dynamic, single-page web applications.

• Angular uses TypeScript for building applications.

• It provides features like data binding, dependency injection, and routing.

• Examples of popular Angular applications include Gmail and Netflix.

Creating Threads in Java

• Extending the Thread class and overriding the run() method

• Implementing the Runnable interface and passing it to a Thread constructor

• Using Executor framework to create and manage threads

• Using Callable and Future interfaces to create threads that return values

Java 8 features like streams are used in Spring Boot for efficient data processing.

• Java 8 introduced streams for functional-style operations on collections.

• Streams allow for parallel processing of data, improving performance.

• Spring Boot applications can leverage streams for efficient data manipulation.

• Example: Using streams to filter and map data in a Spring Boot REST API.

I have worked on various projects including software development, system implementation, and process improvement.

• Implemented Agile methodology in software development projects to increase efficiency and collaboration

• Led cross-functional teams in daily stand-up meetings, sprint planning, and retrospectives

• Utilized tools such as Jira and Trello to track progress and manage tasks

• Worked on projects in industries such as finance, healthcare, and technology

Profiles in Spring Boot allow you to define different configurations for different environments.

• Profiles are used to customize application behavior based on the environment it is running in.

• You can define profiles in application.properties or application.yml using 'spring.profiles.active' property.

• Common profiles include 'dev', 'test', and 'prod' for development, testing, and production environments.

• You can have different configuration values for each profile, such as databas...read more

Concurrent hash map is used for thread-safe operations on a hash map.

• Concurrent hash map allows multiple threads to access and modify the map concurrently without causing any data inconsistency or corruption.

• It is useful in scenarios where multiple threads need to access a shared hash map, such as in a multi-threaded server application.

• Java provides a built-in implementation of concurrent hash map in the java.util.concurrent package.

• Example: A web server that maintains a cach...read more

LRU (Least Recently Used) is a cache eviction policy where the least recently accessed items are removed from the cache when it reaches its capacity.

• LRU cache stores key-value pairs with a maximum capacity. When the cache is full, the least recently used item is evicted to make space for new items.

• Each time a key is accessed in the cache, it is moved to the front of the cache to indicate it was the most recently used item.

• If a new key needs to be added to a full cache, the le...read more

Pipe operator is a symbol used in programming languages to pass the output of one function as input to another function.

• Pipe operator is represented by | in many programming languages.

• It allows for cleaner and more readable code by chaining functions together.

• Example: x |> f |> g is equivalent to g(f(x)).

Tools for calculating defect density include defect tracking tools, spreadsheets, and specialized software.

• Defect tracking tools like Jira or Bugzilla can automatically calculate defect density based on reported issues.

• Spreadsheets can be used to manually calculate defect density by dividing the total number of defects by the size of the software.

• Specialized software such as Quality Center or TestRail may have built-in features for calculating defect density.

• Defect density fo...read more

There are multiple methods to create a singleton service in software development.

• Using a static member variable

• Using a static method to return a single instance

• Using an enum

• Using a synchronized block

Higher order functions are functions that can take other functions as arguments or return functions as results.

• Higher order functions can accept functions as parameters.

• Higher order functions can return functions as output.

• Examples include map, filter, and reduce functions in JavaScript.

The development of an application requires a thorough understanding of the requirements and the target audience. It also involves selecting the appropriate technology stack and following best practices.

• Identify the requirements and target audience

• Select the appropriate technology stack

• Follow best practices such as modular design, code reviews, and testing

• Ensure scalability and security

• Consider user experience and design

• Continuously update and maintain the application

APIs can be exposed from frameworks using various methods such as annotations, configuration files, and code generation.

• Use annotations to mark methods or classes as API endpoints

• Configure the framework to generate API documentation and code

• Use code generation tools to create API code from framework code

• Ensure proper security measures are in place to protect the API

• Examples include Spring Boot, Django, and Ruby on Rails

An interface is used to define a contract between two components in a system.

• An interface defines a set of methods that a class must implement.

• Interfaces are used to achieve abstraction and loose coupling.

• Interfaces are used to create reusable code.

• Interfaces are used to enable polymorphism.

• Interfaces are used in many programming languages, including Java, C#, and TypeScript.

The load function is used to load data from a data source, while the with function is used to specify additional options or parameters for a query or operation.

• Load function is used to retrieve data from a data source

• With function is used to add additional options or parameters to a query or operation

• Load function is essential for fetching data, while with function is optional for providing additional details

Optimizing a React Native application involves improving performance and reducing resource usage.

• Use PureComponent and shouldComponentUpdate to prevent unnecessary re-renders

• Implement virtualized lists for long lists to improve performance

• Minimize the use of third-party libraries and optimize the ones you do use

• Use native modules for performance-critical tasks

• Optimize images and assets for smaller file sizes

REST API best practices include using meaningful resource URIs, proper use of HTTP methods, versioning, security measures, and documentation.

• Use meaningful resource URIs to represent entities and relationships

• Properly use HTTP methods (GET, POST, PUT, DELETE) for CRUD operations

• Implement versioning to manage changes in API

• Implement security measures such as authentication and authorization

• Document API endpoints, parameters, and responses for developers

Custom hooks in React are reusable functions that allow you to extract component logic into separate functions.

• Custom hooks should start with 'use' keyword.

• Custom hooks can be used to share logic between components.

• Example: useFetch custom hook for handling data fetching in components.

MVC Lifecycle is the sequence of events that occur in the Model-View-Controller architectural pattern.

• MVC stands for Model-View-Controller.

• The lifecycle starts with a user request.

• The controller receives the request and processes it.

• The controller updates the model with the necessary data.

• The view is then updated with the updated model data.

• The updated view is sent back to the user as a response.

HashMap is a non-synchronized implementation of Map interface while HashTree is a synchronized implementation of Map interface.

• HashMap is faster than HashTree as it is non-synchronized.

• HashTree is thread-safe while HashMap is not.

• HashMap allows one null key and multiple null values while HashTree does not allow null keys or values.

• HashTree maintains the order of elements while HashMap does not.

• HashMap is generally used in single-threaded applications while HashTree is used in...read more

Our clients come from various domains and verticals, including healthcare, finance, retail, and technology.

• We work with clients in healthcare, finance, retail, and technology industries

• Our clients range from small businesses to large corporations

• We focus on building long-term relationships with our clients

• We provide customized solutions to meet the unique needs of each client

Factory pattern is a creational design pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.

• Create an interface or abstract class for the factory with a method to create objects

• Create concrete classes that implement the factory interface and return specific types of objects

• Client code uses the factory to create objects without knowing the specific class being instantiated

React Native works by running JavaScript code on a separate thread and communicating with native modules through a bridge.

• React Native runs JavaScript code on a separate thread called the JavaScript thread.

• It communicates with native modules through a bridge, which allows JavaScript to interact with platform-specific APIs.

• The bridge passes messages between the JavaScript thread and the native modules, enabling seamless communication.

• React Native uses a virtual DOM to efficien...read more

Angular runs its project using the Angular CLI, which provides a command-line interface for various project tasks.

• Angular projects are run using the 'ng serve' command to start a development server.

• The Angular CLI handles tasks such as building, testing, and deploying the project.

• Configuration for the project can be done using the 'angular.json' file.

• Dependencies are managed using npm or yarn.

• Angular applications are typically structured using components, services, modules, a...read more

Polymorphism is the ability of an object to take on many forms.

• Polymorphism allows objects of different classes to be treated as if they are objects of the same class.

• It can be achieved through method overloading and method overriding.

• Example: A parent class Animal can have multiple child classes like Dog, Cat, and Cow. All these child classes can have their own implementation of the method 'makeSound', which can be called using the parent class reference variable.

• Polymorphis...read more

HDFS stands for Hadoop Distributed File System, a distributed file system designed to store and manage large amounts of data across multiple machines.

• HDFS is a key component of the Hadoop ecosystem, providing high-throughput access to application data.

• It is designed to be fault-tolerant, scalable, and reliable.

• HDFS divides files into blocks and stores multiple copies of each block across different nodes in a cluster.

• It allows for parallel processing of data across the cluster...read more

Async in NodeJs allows non-blocking execution of code, improving performance by handling multiple operations simultaneously.

• Async functions in NodeJs use callbacks, promises, or async/await to handle asynchronous operations.

• By using async functions, NodeJs can continue executing other code while waiting for I/O operations to complete.

• Async functions help prevent blocking the event loop, allowing for better scalability and performance.

• Example: Using fs.readFile to asynchronous...read more

Components of SSIS include Control Flow, Data Flow, Connection Managers, Event Handlers, Variables, Parameters, and Logging.

• Control Flow: Defines the workflow of tasks to be executed

• Data Flow: Moves data between sources and destinations

• Connection Managers: Define connections to data sources

• Event Handlers: Respond to events during package execution

• Variables: Store values that can be used throughout the package

• Parameters: Allow for dynamic values to be passed to packages

• Logging...read more

Agile metrics are key performance indicators used to measure the progress and success of agile projects.

• Agile metrics help teams track productivity, quality, and delivery time.

• Examples of agile metrics include sprint burndown charts, velocity, lead time, and cycle time.

• These metrics provide insights into team performance and help identify areas for improvement.

The onboarding process of a banking application involves gathering necessary information from customers to create accounts and provide access to services.

• Collecting personal information such as name, address, contact details, and identification documents.

• Verifying the information provided through identity verification processes.

• Setting up login credentials for customers to access their accounts online.

• Explaining the features and services available on the banking application.

• E...read more

ASAP methodology is a framework used for SAP implementation projects.

• ASAP stands for Accelerated SAP.

• It is a step-by-step approach to implement SAP solutions.

• It includes five phases: Project Preparation, Business Blueprint, Realization, Final Preparation, and Go-Live and Support.

• Each phase has its own set of deliverables and tasks.

• ASAP methodology helps to ensure that the implementation project is completed on time, within budget, and meets the business requirements.

let, var, and const are keywords used for variable declaration in JavaScript.

• let is block-scoped and can be reassigned.

• var is function-scoped and can be reassigned.

• const is block-scoped and cannot be reassigned, but its value can be mutated.

A deadlock is a situation in which two or more competing actions are each waiting for the other to finish, preventing any of them from progressing.

• Occurs in concurrent programming when two or more threads are blocked forever, waiting for each other to release a resource

• Can happen in database systems when two transactions are each waiting for the other to release a lock

• Can be resolved by careful resource allocation and avoiding circular dependencies

Collections in Java are used to store and manipulate groups of objects.

• Java provides several collection classes like ArrayList, LinkedList, HashSet, etc.

• Collections can store objects of any type, including user-defined classes.

• Collections provide methods for adding, removing, and accessing elements.

• They also offer functionalities like sorting, searching, and iterating over elements.

• Example: ArrayList names = new ArrayList<>(); names.add("John"); names.add("Jane");

INVEST criteria are used to evaluate user stories for their quality and effectiveness.

• Independent - the user story should be self-contained and not dependent on other stories

• Negotiable - the details of the story can be negotiated and changed as needed

• Valuable - the story should provide value to the user or customer

• Estimable - the story should be able to be estimated for time and effort

• Small - the story should be small enough to be completed in a single sprint

• Testable - the st...read more

DevOps screening involves testing various tools for their effectiveness.

• DevOps tools should be tested for their ability to automate processes and improve collaboration.

• Tools like Jenkins, Ansible, Docker, and Kubernetes are commonly used in DevOps.

• Screening should also consider the tool's compatibility with the existing infrastructure.

• Performance, security, and scalability are other important factors to consider during screening.

React is a JavaScript library for building user interfaces. Redux is a predictable state container for JavaScript apps.

• React is used for building reusable UI components

• It uses a virtual DOM for efficient rendering

• Redux is used for managing application state

• It follows a unidirectional data flow pattern

• Redux provides a single source of truth for the application state

Event loop in Node.js is a mechanism that allows Node.js to perform non-blocking I/O operations.

• Event loop is responsible for handling asynchronous operations in Node.js.

• It allows Node.js to perform multiple operations concurrently without blocking the execution.

• Event loop continuously checks the event queue for any pending tasks and executes them in a non-blocking manner.

• Example: setTimeout() function in Node.js uses event loop to schedule the callback function after a speci...read more

Handling difficult clients requires patience, communication skills, and problem-solving abilities.

• Listen actively to understand their concerns

• Stay calm and professional, even if they are being difficult

• Set clear boundaries and expectations

• Offer solutions and compromises to address their issues

• Seek feedback and address any misunderstandings promptly

The task is to count the occurrences of each character in a given string.

• Iterate through the string and use a HashMap to store the count of each character.

• Convert the string to char array for easier manipulation.

• Handle both uppercase and lowercase characters separately if needed.

Scrum is an agile methodology used for project management, emphasizing teamwork, accountability, and iterative progress.

• Scrum involves breaking down projects into small, manageable tasks called user stories.

• It includes daily stand-up meetings to discuss progress and obstacles.

• Scrum uses time-boxed iterations called sprints to deliver incremental value.

• Roles in Scrum include Product Owner, Scrum Master, and Development Team.

• Key artifacts in Scrum include the Product Backlog, S...read more

BDD framework stands for Behavior Driven Development framework, which focuses on the behavior of the system from the end user's perspective.

• BDD framework uses natural language to describe the behavior of the system

• It helps in collaboration between developers, testers, and business stakeholders

• Popular BDD frameworks include Cucumber, SpecFlow, and JBehave

Risk mitigation techniques are strategies used to minimize or prevent potential negative impacts on a project.

• Identify and assess potential risks

• Develop a risk management plan

• Implement risk response strategies

• Monitor and control risks throughout the project

• Examples include contingency planning, risk transfer, and risk avoidance

Governor limits in Salesforce are predefined limits that prevent abuse and ensure fair resource allocation.

• Governor limits apply to various aspects of Salesforce, such as Apex code, SOQL queries, DML operations, and email invocations.

• These limits are in place to maintain system performance, prevent infinite loops, and protect against resource hogging.

• Examples of governor limits include maximum CPU time, maximum number of SOQL queries, maximum heap size, and maximum number of ...read more

API testing is testing the functionality, reliability, performance, and security of APIs.

• API testing involves testing the communication between different software systems using APIs.

• It focuses on verifying the functionality, performance, reliability, and security of APIs.

• API testing can be done at different levels such as unit testing, integration testing, and end-to-end testing.

• Tools like Postman, SoapUI, and JMeter are commonly used for API testing.

• Examples of API testing i...read more

Hadoop is an open-source software framework for storing and processing large datasets in a distributed computing environment.

• Hadoop consists of the Hadoop Distributed File System (HDFS) for storage and MapReduce for processing.

• It allows for the distributed processing of large data sets across clusters of computers.

• Hadoop is designed to scale from a single server to thousands of machines, each offering local computation and storage.

• Popular tools in the Hadoop ecosystem include...read more